The present invention relates to a process for rendering nacreous pigments hydrophobic. The pigments are based on mica platelets coated with metal oxides.
Nacreous pigments based on mica platelets coated with metal oxides are used in many technical fields, such as, for example, in cosmetics, as pigments for nail lacquer, lipsticks, powder and the like, and also for pigmenting all types of plastics and lacquers. So that these nacreous pigments can display their properties in an optimum manner, it is necessary for the pigments to be in homogeneous distribution without agglomerates being formed.
Difficulties in achieving a homogeneous distribution arise again and again, especially when nacreous pigments are incorporated into organic formulations. It is known that improved incorporation of normal colored pigments into, for example, plastics is achieved by rendering the pigments hydrophobic. In the case of nacreous pigments, whose color is produced by interference phenomena in the thin metal oxide coatings, it must be expected that measures for rendering them hydrophobic would substantially influence the nacreous luster.
In fact, even today, no such process has been disclosed by which nacreous pigments can be rendered hydrophobic without deleterious effect on the luster although such pigments have been known for more than 20 years.